1. Field
Example embodiments of the present invention relate to organic light emitting display devices and methods of operating the organic light emitting display devices.
2. Description of the Related Art
An organic light emitting display device implemented using a red, green, and blue (RGB) independent deposition method may have various characteristics, such as relatively low power consumption and a relatively high contrast ratio (CR), and thus the RGB independent deposition method has been widely used. In the RGB independent deposition method, patterning for each color of light is performed using fine metal masks. However, the RGB independent deposition method may be difficult to apply to a large scale substrate due to precision problems in aligning the fine metal masks, and a mask sagging phenomenon that may occur as the size of masks increases.
A white organic light emitting diode-color filter (WOLED-CF) method using a white organic light emitting diode in conjunction with a color filter has received much attention in consideration of improving processability and yield. A white organic light emitting diode can be realized by forming a plurality of organic light emitting materials that respectively emit red, green, and blue colors in an organic light emitting layer or by forming complementary pairs of organic light emitting materials in an organic light emitting layer. However, in the WOLED-CF method, white light must be filtered through a color filter, and thus the optical transmittance is relatively low when compared to that of the RGB independent deposition method. In order to maximize the optical efficiency, an RGBW pixel structure including a white (W) sub-pixel having no color filter as well as RGB sub-pixels having color filters has been developed.
However, in an organic light emitting display device having the RGBW pixel structure, because a luminance of a W sub-pixel having no color filter is generally twice as high as a sum of luminances of RGB sub-pixels having color filters, a simultaneous contrast phenomenon, in which a pure color looks darker because of a bright white background, may occur. Further, because the organic light emitting display device having the RGBW pixel structure drives one sub-pixel per pixel when white light is emitted using the W sub-pixel, and drives three sub-pixels per pixel when the white light is emitted using the RGB sub-pixels, the luminance of the W sub-pixel may be different from the luminance of the RGB sub-pixels due to a loading effect according to a driving amount of the organic light emitting display device.